* In terms of water content: Yes, salt crystals are considered dry. They are made of sodium chloride (NaCl), which is a solid compound with a very low water content.

* In terms of water activity: No, salt crystals are not considered dry. Water activity is a measure of the water available for chemical reactions and microbial growth. Salt crystals have a water activity of about 0.75, which means they can still support some microbial growth.

So, while salt crystals are considered dry in the sense that they don't contain significant amounts of free water, they can still be considered "wet" in terms of their water activity.